The natural history, quantified cutaneous sensation, nerve conduction in vivo and vitro, morphometry and pathology of human neuropathy is being studied to provide information on classification, prognosis, three-dimensional pathology, and mechanisms of fiber degeneration in amyotrophic lateral sclerosis, dominantly inherited spastic paraplegia, dominantly inherited olivo-ponto-cerebellar degeneration, Hereditary Motor and Sensor Neuropathy - Type II, Hereditary Motor Neuropathy - Type I, kinships with Charcot joints but without loss of sensation and in such metabolic diseases as diabetes mellitus. The morphometric and pathologic factors underlying pain in peripheral neuropathy is being studied. The mechanisms of segmental demyelination in lead neuropathy are being studied utilizing pathologic evaluation, a statistical analysis of Schwann cell damage, a study of blood-nerve barrier, a study of interstitial pressure and a study of x-ray microanalysis. To analyze the effect of removing the target tissue of motoneurons and of primary afferent neurons, we are evaluating their number and size distribution after hind limb ablation in cats. We are analyzing the fatty acid composition of serum and rbc's in a variety of inherited neuropathies. We are studying the LCAT reaction in various inherited neuropathies. BIBLIOGRAPHIC REFERENCE: Study of quantified cutaneous sensation and morphometry of sural nerve demonstrated that primary afferent nerves may be affected in this disorder (Dyck, P.J. et al: Frequency of nerve fiber degeneration of peripheral motor and sensory neurons in amyotrophic lateral sclerosis: Morphometry to deep and superficial peroneal nerves. Neurol. 25:781-787, Aug. 1975.)